The Vietnam War was the longest in American history, with approximately 3 million American troops serving in Vietnam. Nearly 20 million gallons of herbicides were sprayed in Vietnam and Laos between 1961 and 1971, including more than 12 million gallons of dioxin-contaminated Agent Orange. US forces dropped more bombs in Vietnam than in both World War II and Korea combined. Millions of Vietnamese civilians, tens of thousands of Vietnam veterans, workers and others were exposed to the herbicides and many more to aerial bombardment and ground combat. Now, more than 35 years after the last Agent Orange spray mission and more than thirty years since the withdrawal of all American troops, no sufficiently large epidemiological, ecological or health care delivery study has taken place to assess the impact of these exposures. To a large extent such studies have been stymied by inadequate exposure information. The principal investigator has recently developed exposure methodologies for epidemiological studies using the historical reconstruction of military spray and troop records under a contract to the National Academy of Sciences and has been able to shed considerable light on the extent of spraying and provide accurate estimates of levels of dioxin contamination and numbers of people directly exposed. Her research team has created a geographic information system that contains information on spraying, troop movement and population census data. These data, published as a cover article in Nature and elsewhere, only scratch the surface of available archival materials. We propose to: a) continue archival research to identify additional relevant electronic and paper records relating to herbicide exposures, troop locations, aerial bombing and ground conflict, and transform them into user-friendly, documented files;b)develop a website, maintained at Columbia University, with the downloadable files;c)provide access to the Vietnam geographical information system software developed by the Stellman team. The website will be constructed to serve as a complete guide to military records and relevant related resources in our collection and will document the historical context in which the data were collected and the process we used to clean them and bring them into a uniform, modern format. The website will also contain methodological guidance for the use of the data in health studies and analytical reviews, some of which will also be submitted for peer-reviewed publication.